Food warmers are widely used in restaurant kitchens to maintain batches of prepared foods at a predetermined temperature while portions thereof are served from time to time. Typically, a food warmer consists of a heated basin, usually built into a counter surface, into which various standard-sized food pans can be placed.
Health regulations (as well as taste considerations) require food stored in warmers to be maintained at a uniform temperature at all points within the pan, an objective which is difficult to achieve in an open warmer. Also, the gas or electricity used to keep foods warm is a major expense in a restaurant operation, and loss of moisture in warmed foods is a substantial problem.
Various types of food warmer covers have previously been used to prevent heat and moisture loss. The simplest type, a hinged flat cover, presents handling problems because it gets very hot, and it also tends to get in contact with the food when pans are very full.
To overcome these disadvantages, box-type covers have previously been proposed. These covers had an inclined front opening with a pivotable door which could be conveniently pivoted upwardly into the cover enclosure to access the front portion of the food warmer (the back portion being usually used to store a reserve pan of food). This type of cover, though an improvement over the flat cover, still had some disadvantages: it tended to direct heat or steam toward the cook's arm when opened, and it occupied a substantial amount of space without an attendant increase in food storage capacity. Also, it allowed substantial amounts of heat or steam to escape, and it was somewhat difficult to clean.